Characterization of pure and doped potassium hydrogen tartrate single crystals grown in silica gel

Growth of pure‐, sodium‐ and lithium‐ doped potassium hydrogen tartrate single crystals by gel technique is reported. Growth conditions conducive for the growth of single crystals are worked out. The crystals are characterized by using powder XRD, SEM, FTIR, AES, EDAX, CH analysis and thermoanalytical techniques. The stoichiometric composition for the grown crystals are established as KHC₄H₄O₆.H₂O, (K)_0.98(Na)_0.02.H₂O and (K)_0.94(Li)_0.06HC₄H₄O₆.H₂O. Doping of sodium and lithium in the pure potassium hydrogen tartrate single crystals is found to influence the size, perfection, morphology, crystal structure and the thermal stability of crystals. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

XRD,thermal and FTIR studies on gel grown DL‐Phenylalanine crystals

Phenylalanine [C₉H₁₁NO₂] is one of the essential amino acids in humans. DL‐phenylalanine was crystallized in silica gel under suitable pH conditions by reduction of solubility method. The grown crystals were characterized by density measurement and X‐ray powder diffraction. Fourier transform infrared spectroscopy, and thermogravimetric analysis were also carried out. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and characterization of L‐alanine doped KDP crystals

Potassium Dihydrogen Phosphate (KDP) is an excellent inorganic nonlinear optical (NLO) material with different device applications. Most of amino acids possess NLO property; therefore, it is of interest to dope them in KDP crystals. In the present study, amino acid L‐alanine doped KDP crystals were grown by slow aqueous solvent evaporation technique. The doping of L‐alanine was confirmed by the paper chromatography, the CHN analysis and the FT‐IR spectroscopy. The powder XRD was carried out to assess the single phase nature of the samples. The effect of doping on thermal stability of the crystals was studied by TGA and the kinetic and thermodynamic parameters of dehydration were evaluated. As the amount of doping increased the thermal stability of crystals decreased. However, the second harmonic generation (SHG) efficiency and the UV‐Vis spectroscopy studies indicated that as the L‐alanine doping increased the SHG efficiency and optical transmission percentage increased. The dielectric behavior of the samples has been studied. The variation of dielectric constant, dielectric loss (tanδ), a.c.resistivity and a.c.conductivity with frequency of applied field in the range from 100 Hz to 100 kHz was studied. The dielectric constant and dielectric loss decreased with increase the value of frequency of applied field. The dielectric constant and the dielectric loss values of L‐alanine doped KDP crystals were lower than the pure KDP crystals. The results are discussed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis of L‐valine crystals

L‐valine (C₅H₁₁NO₂), an essential amino acid of monoclinic space group P2₁, Z = 4 and lattice parameters a = 9.688 (2) Å, b = 5.267 (1) Å, c = 11.980 (2) Å and β = 90.75 (1)° and of size: 6.0 mm across and 0.5 mm thick was crystallized in silica gel under suitable pH conditions by reduction of solubility method. Density measurement and single crystal X‐ray diffraction were used to characterize the grown crystals. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopic (SEM) studies were made and crystal packing also discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Aspergillums Niger assisted crystal growth of calcium tartrate: an alternative method to grow crystals

A novel method of growing calcium tartrate single crystals was developed in which the crystals were hanging freely in solution assisted by fine filaments of fungi (Aspergillums niger). Spores of A. niger were inoculated and allowed to grow in the supernatant solution of calcium chloride and tartaric acid (1:1) on the silica hydro‐gel impregnated with orthophosphoric acid. Transparent, prismatic, calcium tartrate crystals were grown hanging in the filamentous network of the fungi after 10 days in the supernatant solution. This network of the mycelium facilitated and mimicked the gel. The grown crystals were identified as calcium tartrate trihydrate and characterized by powder XRD, FTIR and TGA. This technique provides an alternate and a novel technique to grow crystals. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

XRD,thermal, FTIR and SEM studies on gel grown γ‐glycine crystals

Glycine is the smallest among amino acids. The polymorphs, α‐ and γ‐forms of glycine were crystallized in silica gel by reduction of solubility method. The grown crystals were characterized by single crystal X‐ray diffraction studies and density determination. Fourier transform infrared spectroscopic studies and thermogravimetric analysis of γ‐glycine were also conducted. Morphological and scanning electron microscopic (SEM) studies were also made and compared with the crystal packing. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and characterization of gel grown calcium pyrophosphate tetrahydrate crystals

Formation of calcium pyrophosphate dihydrate (CPPD) crystals in soft tissues such as cartilage, meniscus and synovial tissues lead afflictions. The appearance of these crystals in the synovial fluid give rise to acute arthritis attack, which is known as pseudo‐gout. The growth of calcium pyrophosphate crystals in gel medium can mimic the growth in a body. In the present study, calcium pyrophosphate tetrahydrate (CPPT) crystals are grown by a single diffusion gel growth technique and characterized by powder XRD, FT‐IR spectroscopy, TGA, kinetic and thermodynamic studies of dehydration and dielectric studies. Monoclinic crystals structure, presence of P‐O bonds and four water molecules are confirmed from powder XRD, FT‐IR and TGA studies, respectively. The dielectric investigation suggests the reduction in dielectric constant with increase in frequency. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Characterization of lead(II)chloride single crystals grown in silica gel

Acousto‐optical materials play an important role in acousto‐optic devices as acousto‐optic modulators. Lead(II) chloride is an acousto‐optical material, having high figure of merit approximately ten times greater than that of lead molybdate, which is an efficient acousto‐optical material. It also possesses high birefringence, low attenuation coefficient, wide transparency range and good mechanical properties. This paper discusses in detail, the growth of single crystals of lead(II) chloride in silica gel by the process of diffusion in a highly acidic medium. Needle‐type lead(II) chloride crystals have been obtained. The crystal system is confirmed to be orthorhombic by powder X‐ray diffraction analysis. To study the optical transparency of the grown crystal, the transmission spectrum has been recorded in the range 190 – 1100 nm. Thermal stability of the crystal is also studied. Results are discussed in detail. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal Growth of some Urinary Stone Constituents: I. In‐Vitro Crystallization of L‐Tyrosine and its Characterization

L ‐Tyrosine (C₉H₁₁NO₃), having morphology of spherulitic needles and long needles, an amino acid constituent of urinary stone, is crystallized in silica gel under suitable pH conditions and by single diffusion and double diffusion methods. The grown crystals were characterized by density measurement, Fourier transform infrared spectroscopy, X‐ray powder diffraction and thermogravimetric analysis.     

Growth of barium oxalate crystals in agar–agar gel and their characterization

Single crystals of barium oxalate have been grown by gel method using agar‐agar gel as media of growth at ambient temperature. The optimum conditions were established by varying various parameters such as concentration of gel, concentration of reactant, gel setting time etc. Prismatic platy shaped transparent crystals were obtained. The grown crystals were characterized through powder X‐ray diffraction (XRD), Fourier transform infrared (FT‐IR) studies, Thermogravimetric (TGA) and Differential thermal analysis (DTA). The compound crystallizes under monoclinic structure with lattice parameters a = 6.6562 Å, b = 8.0464 Å, c = 2.8090 Å, β= 96.832°, and V = 149.38 ų. The FT‐IR spectrum indicates OH and carbonyl group along with the presence of metal‐oxygen bond. The TGA indicates 17.75% weight loss at 550°C from which the decomposition pattern is formulated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Characterization of L‐aspartate crystals grown in gel medium

L‐Aspartate [C₄H₇NO₄], also called as 2‐aminobutanedoioic acid, an organic amino acid was crystallized with the aid of sodium metasilicate gel. Diffusion of the supersaturated solutions in porous gel network by solubility reduction method in silica gel was carried out in our laboratory. The crystals were characterized using powder X‐ray diffraction technique. Fourier transform infrared spectroscopy reveals the presence of functional groups in the crystals. Optical absorbance of the crystals was studied by UV – Visible spectroscopy and the thermal properties were studied by thermo gravimetric analysis. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and characterization of Mn2+ doped calcium l‐tartrate crystals

Single crystals of Mn²⁺ doped calcium levo‐ tartrate tetrahydrate (CLTT) were grown by single diffusion gel growth technique in silica hydro‐gel media. The doping of Mn²⁺ was varied by mixing 0.001M, 0.005M, 0.01M, 0.05M, and 0.1M solutions of MnCl₂ with 1M CaCl₂ solution in equal volumes in the supernatant solutions. The actual amount of Mn²⁺ doping in CLTT crystals was estimated by ICP (Inductively Coupled Plasma) technique. The powder XRD of the samples suggested no significant change in the unit cell dimensions and the presence of any extra phase. The FT‐IR spectra indicated the presence of water molecule, O‐H bond, C‐O bond and carbonyl C=O bond. The EPR spectra confirmed the presence of Mn²⁺ ions in the crystals. The variation of the dielectric constant with temperature confirmed the earlier results of pure calcium tartrate crystals and indicated the ferroelectric nature of the doped crystals. As the amount of doping of Mn²⁺ increased the value of dielectric constant increased. The results are discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Gel growth and characterization of β ‐DL‐methionine

DL‐Methionine [C₅H₁₁NO₂S] is one of the essential amino acids in humans. It has two crystalline forms, viz., α‐ and β‐ methionine. In the present study, β ‐ form is crystallized in silica gel; under suitable pH conditions by single diffusion method. The grown crystals were characterized by density measurement and single crystal X‐ray diffraction. Fourier transform infrared (FTIR) spectroscopic studies, thermal analysis and scanning electron microscopic (SEM) studies were also made as part of the structural studies. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth of ytterbium tartrate trihydrate crystals in silica and agar‐agar gels and their characterization

Single crystals of ytterbium tartrate trihydrate have been grown by gel method using silica and agar‐agar gels as media of growth. The medium of growth influences the morphology of grown crystals, silica gel yielding single and polycrystalline in the form of spherulites whereas agar‐agar gel leading to growth of single and twinned crystals. Materials grown as single crystals have been characterized by using optical and scanning electron microscopy (SEM), EDAX, XRD, FT‐IR, CHN and thermogravimetric techniques. The stoichiometry of the grown single crystals is suggested to be Yb(C₄H₄O₆) (C₄H₅O₆).3H₂O. The FT‐IR spectrum shows the presence of singly as well as doubly ionized tartrate ligands. Results of thermal analysis indicate that the material is thermally stable up to a temperature of 200 °C. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal growth of some urinary stone constituents: III. In‐vitro crystallization of L‐cystine and its characterization

L‐Cystine (‐SCH_2· CHNH_2· COOH), having the morphology of hexagonal plates, an amino acid constituent of urinary stone, is crystallized in silica gel under suitable pH conditions by double diffusion method. The grown crystals were characterized by density measurement, Fourier transform infra‐red spectroscopy, X‐ray powder diffraction and thermogravimetric analysis. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of annealing temperatures on properties of sol‐gel grown ZnO‐ZrO2 films

Mixed ZnO‐ZrO₂ films have been obtained by sol‐gel technology. By using spin coating method, the films were deposited on Si and glass substrates. The influence of thermal annealings (the temperatures vary from 400 °C to 750 °C) on their structural properties has been studied. The structural behavior has been investigated by the means of XRD and FTIR techniques. The results revealed no presence of mixed oxide phases, the detected crystal phases were related to the hexagonal ZnO and to crystalline ZrO₂. The sol‐gel ZnO‐ZrO₂ films showed polycrystalline structure with a certain degree of an amorphous fraction. The optical transmittance reached 91% and it diminished with increasing the annealing temperatures. The optical properties of the sol‐gel ZnO‐ZrO₂ films, deposited on glass substrates are excellent with high transparency and better then those of pure ZrO₂ films, obtained at similar technological conditions. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal growth of some urinary stone constituents: II. In‐vitro crystallization of hippuric acid

Hippuric acid [C₆H₅CONHCH₂COOH], one of the organic chemical constituents of urinary stone is crystallized in silica gel under suitable pH conditions by double diffusion method. The grown crystals were characterized by density measurement, Fourier transform infrared spectroscopy, X‐ray powder diffraction and thermogravimetric analysis.     

Growth and characterization of Struvite‐K crystals

Struvite‐K is the natural potassium equivalent to Struvite. Struvite‐K crystals were grown by single diffusion gel growth technique in silica hydro gel medium. Struvite‐K crystals with different morphologies having transparent to translucent diaphaneity were grown with different growth parameters. The phenomenon of Liesegang rings was also observed with some particular growth parameters. The crystals were characterized by powder XRD, FT‐IR, TGA and dielectric study. The powder XRD results of Struvite‐K confirmed the orthorhombic crystal structure. The FT‐IR spectrum proved the presence of water of hydration, metal – oxygen bond and P – O bond. The TGA, DSC and DTA were carried out simultaneously. It was found that crystals started dehydrating and decomposing from 75 °C and finally at 600 °C temperature it became 64.14% of the original weight and remained almost constant up to the end of analysis. From the thermo‐gravimetry, the numbers of the water molecules associated with the crystal were calculated and found to be 5. The kinetic and thermodynamic parameters of dehydration / decomposition process were calculated. The variation of dielectric constant with frequency of applied field was studied in the range from 400 Hz to 100 kHz, which exhibited the decreasing nature of the dielectric constant as frequency increased. The dielectric study showed that a.c. conductivity increased and consequently the a.c. resistivity decreased with the increase in frequency. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

FT‐IR spectroscopic and thermal studies on pure and impurity added calcium tartrate tetrahydrate crystals

Pure and impurity (strontium) added calcium tartrate tetrahydrate single crystals were grown by the gel method. The FT‐IR spectra of these crystals were recorded in the wavenumber range 400–4000 cm^–1. The thermograms of the grown crystals were recorded in the temperature range 50–900 °C. FT‐IR spectra reveals the presence of water molecules, O‐H bond, C‐O and carbonyl C=O bonds. The thermograms show that these crystals are thermally unstable and decompose into its oxide through many stages. DTA curve of the pure crystal shows three endothermic and one exothermic peaks. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and characterisation of gadolinium samarium oxalate single crystals

Single crystals of Gadolinium Samarium Oxalate (GSO) are grown by gel method. The crystals are pale yellowish in colour. Morphology and size of the crystals are found to depend on pH of the medium, gel density, concentration of the reactants and acidity of the feed solution. The crystallinity of the grown sample was confirmed by X‐ray diffraction studies and the lattice parameters were determined. X‐ray diffractogram shows well defined peaks. IR spectrum confirms the presence of water molecules and carboxylic group. EDAX analysis confirms the presence of Gd and Sm in the sample. The thermal decomposition behaviour of the crystal was analysed using TGA and DTA studies. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)